1. Field of the Invention
The present invention relates to an armature and more specifically to an armature for use in a motor.
2. Description of the Related Art
JP-A 2003-079080 describes a stator including a stator core, coils, and insulating members, as an example of a conventional armature used in a motor. In the stator described in this publication, each insulating member, which is tubular in shape, is arranged between a separate one of the coils and a corresponding one of magnetic pole teeth of the stator core (see, e.g., claim 1 of JP-A 2003-079080). In addition, each insulating member described in JP-A 2003-079080 is made up of two insulating member pieces joined to each other (see, e.g., claim 3 of JP-A 2003-079080). Moreover, the two insulating member pieces described in JP-A 2003-079080 are fitted to each other such that end portions of the insulating member pieces overlap with each other (see paragraph [0024] and FIG. 3 of JP-A 2003-079080).
In the stator described in JP-A 2003-079080, however, fitting portions of the two insulating member pieces together define an increased thickness portion of the insulating member (see paragraph [0024] and FIG. 3 of JP-A 2003-079080). The increased thickness portion is the thickest portion of the insulating member. According to the above structure, a space in which the coil is to be arranged is narrowed by each increased thickness portion of the insulating member. In order to increase the number of turns of each coil while preventing an excessive increase in the size of the motor, it is desirable to minimize an increase in the thickness of a portion of the insulating member where the two insulating member pieces overlap with each other.
However, simply reducing the thickness of each end portion of each insulating member piece would result in difficulty in ensuring a sufficient strength of each end portion of each insulating member piece. A decrease in the strength of each end portion of each insulating member piece might permit any of the insulating member pieces to be damaged by, for example, contact between the end portions of the insulating member pieces when the two insulating member pieces are fitted to each other. Moreover, a decrease in the thickness of each end portion of each insulating member piece would narrow a channel through which a molten resin flows in a resin molding process. This might lead to a decreased precision in molding.